Geology

My experiments with volcanoes

The Earth's Beginning

Outlines of the Earth's History: A Popular Study in Physiography

Essay on the Theory of the Earth

The Elements of Geology

Inside Illinois: Mineral Resources

The Chain of Life in Geological Time

Urban Exploration Tips

Deep Cave Descents

Arctic Night Wonders

Soaring Glider Flights

Jungle Camp Advice

Navigation Without Tools

Prairie, Peak, and Plateau: A Guide to the Geology of Colorado

Geology

The Geologic Setting of the John Day Country: Grant County, Oregon

Deep Cave Missions

Arctic Ice Treks

Preliminary Report on Gowganda Mining Division District of Nipissing Ontario

Climate and Time in Their Geological Relations